Fuel injection device for internal combustion engines

ABSTRACT

An injection device for internal combustion engines with injection valves and an excess pressure valve controllable by an adjustment of throttle valves for control of the pressure of the introduced fuel.

United States Patent Klein 1 May 16, 1972 [54] FUEL INJECTION DEVICE FOR[561 References Cited INTERNAL COMBUSTION ENGINES UNITED STATES PATENTS[72] lnventor: Heinz Klein, Wolfsburg, Germany 2,136,959 1 1/ 1938Winfield ..123/139.18 1,664,615 4/1928 French ..123/32 AB [73] Ass1gnee:Volkswagenwerk Aktiengesellschaft, Wolf- 1,679,159 7/1928 French W123/32 AE Sburg, Germany R18,195 9 1931 French .....123/32 AB 2 Filed: N06, 19 9 2,310,773 2/1943 Fuscaldo .....l23/32 AE 2,410,728 11/1946Fuscaldo 123/32 A13 [21] Appl. No.: 874,146 3,105,478 10/1963 Lyon....123/139.18 3,319,613 5/1967 Begley et a1. ..l23/32 EA 1 ForeignApPlication Priority Data Primary Examiner-Laurence M. GoodridgeAssistant Examiner-Cort Flint Nov. 8, 1968 Germany ..P 18 07 773.1A'tomey watson Cole Grindle & Watson [52] US. Cl. [23/32 AE, 123/119[57] ABSTRACT 51 1111. C1 ..F02b 3/10 1 [53] Field of Search "1233/32EA, 32 AE, 13913, 9, An injection device for internal combustion engineswith in- 123/32 jection valves and an excess pressure valve controllableby an adjustment of throttle valves for control of the pressure of theintroduced fuel.

3 Claims, 1 Drawing Figure FUEL INJECTION DEVICE FOR INTERNAL COMBUSTIONENGINES The invention relates to a device for the indirect injection offuel for internal reciprocating combustion engines, that is, a devicewhere the fuel is not injected directly at a high pressure into thecylinders but with a considerably lower pressure into the suction pipein front of the inlet valves. Mechanical arrangements for the variableapportioning of the fuel are relatively expensive because of the highrequirements for precision; therefore injection devices withelectromatnetically controllable injection valves have been known wherethe fuel is injected at a constant pressure and a measured quantity ofthe fuel is provided by electric means through a change in the durationof the opening of the valve.

The present invention has for an object to make this device lessexpensive and to. achieve an increased operating reliability of such adevice and it provides a measured fuel quantity by means of a-variableinjection pressure while the time for opening of the valve remainsconstant. According to the invention, an excess pressure valve forcontrol of the pressure of the introduced fuel is controllable throughan adjustment of the throttle valves.

Further objects will be apparent from the following description whenconsidered in connection with the accompanying drawing in which thesingle FIGURE is a diagrammatic view of a systemfor injecting fuel in anengine cylinder. I

The fuel is sucked in from tank 1 through a filter 2 by an eccentricpump 3 and is pumped with a variable pressure of 2 l5 atmospheres,depending on the engine conditions into the feed lines 4 to theinjection valves 5. The'variable pressure is regulated within the rangeof 2 12 at. by an adjustable excess pressure valve 6. An eccentric 7,which, indicated by the broken line 8, is firmly connected with thethrottle valve 9, imparts the smallest initial stress to the excesspressure valve 6 when the throttle valve 9 is closed and it imparts thegreatest initial stress when the throttle valve 9' is open. In the caseof idling, the pressure amounts to 2 at. and in the case of a maximumr.p.m., to 12 at. For a further increase in pressure during the time ofacceleration of the motor vehicle, a magnetic shutoff valve 10 has beenprovided which can be closed by a contact switch 12 which is closed uponthe fuel gas position of the gas or accelerator pedal 11. In that case,the flow resistance in the return line 13 and 130 will be increased. Thepressure rises to 15 at. and is kept at this value through the excesspressure valve 14. The electric control of the magnetic shutoff valve 10will be described further.

The throttle valve 9 and the eccentric 7 are operated by the gas pedal11. An impulse transmitter 15 for the electronic control of theinjection valves 5 is located in the distributor 16 and it runs withhalf the r.p.m. The eccentric pump 3 conveys four times the requiredquantity of fuel.

The impulse transmitter 15 consists of a collecting ring 17 shownseparately in the right-hand upper part of the figure of the drawing,with a trapezoid shaped impulse cam 17a. The impulse cam 1711 has anupper width which transmits a current impulse of 2 msec. to thecorresponding injection valve 5 in the case of the idling r.p.m. With anincreasing r.p.m., a centrifugal device 18 will lift the collecting ring17 in such a way that the impulse cam 17a will each time have theeffective width which corresponds to the impulse time of 2 msec. In thecase of an idling r.p.m. of 1,000 r.p.m. and a full load r.p.m. of

5,000 r.p.m., the lower width of the cam must then be five times widerthan the upper width of the cam.

The current supply from battery 20 to the injection valves 5 isaccomplished each time whenever the sliding contact 21, which slidescontinuously on the current conducting ring 17b, is connected with thesliding contact 22 by means of the im-- pulse cam 17a. The leading edgeof the impulse contact 17a, viewed in the rotational direction, has beendeveloped slantingly while the rear edge runs perpendicularly. In thisway, the opening phase of the injection valves 5 with the duration ofinjection remaining the same, will be advanced in time as is desirablein operation. I

The current supply for the magnetic valve 10 is likewise controlled bymeans of the collecting ring 17. ln the case of low r.p.m. of the engineand in the case of the gas pedal being pushed completely to the floor,the contact element 19 will slide on the current conducting element 17bof the collecting ring 17. In the case of higher r.p.m., the collectingring 17 is lifted up and the flow of current is interrupted, since thecontact element 19 now slides on the lower currentless part of thecollecting ring 17. The injection pressure can then amount to only amaximum of 12 at.

I claim:

1. An injection device for internal reciprocating combustion engineshaving injection valves mounted in a suction pipe and controllable byelectrical impulses for introducing fuel under variable pressure from afuel supply, comprising;

a'fuel return line connected to said fuel supply,

an adjustable excess pressure valve'for controlling the pressure of thefuel from said fuel supply to said injection valves by varying the fuelflow resistance in said fuel return line,

a throttle vaLve mounted in said suction pipe,

an engine accelerator,

means for connecting said throttle valve and said excess pressure valveto said engine accelerator for simultaneous operation of said adjustablepressure valve and said throttle valve with acceleration anddeceleration of said engine, electromagnetic valve means mounted in saidreturn line for raising the fuel pressure to said injection valves whenoperated,

switching means actuated by said engine accelerator for operating saidvalve means only under substantially full acceleration conditions,

and a contact device for operating said valve means depending on ther.p.m. ofsaid engine.

2. An injection device as in claim 1 further comprising a distributorhaving means responsive to the varying centrifugal force of the rotationof said distributor, means for generating constant duration electricalimpulses for controlling said injection valves and responsive to saidcentrifugal force means.

3. An injection device as in claim 2 wherein said means for generatingelectrical impulses includes adjustable means connected to said meansresponsive to a centrifugal force to be adjusted by said centrifugalforce inversely proportional to the r.p.m. of said engine, an impulsecam driven by said adjustable means, a pair of spaced slidable contactsintermittently interconnected to said impulse cam, and each of saidslidable contacts is respectively connected to the engine battery andsaid injection valves.

1. An injection device for internal reciprocating combustion engineshaving injection valves mounted in a suction pipe and controllable byelectrical impulses for introducing fuel under variable pressure from afuel supply, comprising; a fuel return line connected to said fuelsupply, an adjustable excess pressure valve for controlling the pressureof the fuel from said fuel supply to said injection valves by varyingthe fuel flow resistance in said fuel return line, a throttle vaLvemounted in said suction pipe, an engine accelerator, means forconnecting said throttle valve and said excess pressure valve to saidengine accelerator for simultaneous operation of said adjustablepressure valve and said throttle valve with acceleration anddeceleration of said engine, electromagnetic valve means mounted in saidreturn line for raising the fuel pressure to said injection valves whenoperated, switching means actuated by said engine accelerator foroperating said valve means only under substantially full accelerationconditions, and a contact device for operating said valve meansdepending on the r.p.m. of said engine.
 2. An injection device as inclaim 1 further comprising a distributor having means responsive to thevarying centrifugal force of the rotation of said distributor, means forgenerating constant duration electrical impulses for controlling saidinjection valves and responsive to said centrifugal force means.
 3. Aninjection device as in claim 2 wherein said means for generatingelectrical impulses includes adjustable means connected to said meansresponsive to a centrifugal force to be adjusted by said centrifugalforce inversely proportional to the r.p.m. of said engine, an impulsecam driven by said adjustable means, a pair of spaced slidable contactsintermittently interconnected to said impulse cam, and each of saidslidable contacts is respectively connected to the engine battery andsaid injection valves.